Method for forming fine pitch structures

ABSTRACT

A mold having an open interior volume is used to define patterns. The mold has a ceiling, floor and sidewalls that define the interior volume and inhibit deposition. One end of the mold is open and an opposite end has a sidewall that acts as a seed sidewall. A first material is deposited on the seed sidewall. A second material is deposited on the deposited first material. The deposition of the first and second materials is alternated, thereby forming alternating rows of the first and second materials in the interior volume. The mold and seed layer are subsequently selectively removed. In addition, one of the first or second materials is selectively removed, thereby forming a pattern including free-standing rows of the remaining material. The free-standing rows can be utilized as structures in a final product, e.g., an integrated circuit, or can be used as hard mask structures to pattern an underlying substrate. The mold and rows of material can be formed on multiple levels. The rows on different levels can crisscross one another. Selectively removing material from some of the rows can from openings to form, e.g., contact vias.

REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.12/140,928, entitled METHOD FOR FORMING FINE PITCH STRUCTURES, filedJun. 17, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to techniques for fabricating closelyspaced structures, such as, for example, features in an integratedcircuit.

2. Description of the Related Art

Techniques for forming closely spaced structures have many applications.For example, integrated circuits are continuously being reduced in size.The sizes of the constituent features that form the integrated circuits,e.g., electrical devices and interconnect lines, are also constantlybeing decreased to facilitate this size reduction.

The trend of decreasing feature size is evident, for example, in memorycircuits or devices such as dynamic random access memories (DRAMs),flash memory, static random access memories (SRAMs), ferroelectric (FE)memories, etc. To take one example, DRAM typically includes millions ofidentical circuit elements, known as memory cells. A memory celltypically consists of two electrical devices: a storage capacitor and anaccess field effect transistor. Each memory cell is an addressablelocation that may store one bit (binary digit) of data. A bit may bewritten to a cell through the transistor and may be read by sensingcharge in the capacitor. Some memory technologies employ elements thatcan act as both a storage device and a switch (e.g., dendritic memoryemploying silver-doped chalcogenide glass) and some nonvolatile memoriesdo not require switches for each cell (e.g., magnetoresistive RAM) orincorporate switches into the memory element (e.g., EEPROM for flashmemory).

In another example, flash memory typically includes millions of flashmemory cells containing floating gate field effect transistors that mayretain a charge. The presence or absence of a charge in the floatinggate determines the logic state of the memory cell. A bit may be writtento a cell by injecting charge to or removing charge from a cell. Flashmemory cells may be connected in different architecture configurations,each with different schemes for reading bits. In a “NOR” architectureconfiguration, each memory cell is coupled to a bit line and may be readindividually. In a “NAND” architecture configuration, memory cells arealigned in a “string” of cells, and an entire bit line is activated toaccess data in one of the string of cells.

In general, by decreasing the sizes of the electrical devices thatconstitute a memory cell and the sizes of the conducting lines thataccess the memory cells, the memory devices may be made smaller.Additionally, storage capacities may be increased by fitting more memorycells on a given area in the memory devices. The need for reductions infeature sizes, however, is more generally applicable to integratedcircuits, including general purpose and specialty processors.

The continual reduction in feature sizes places ever greater demands onthe techniques used to form the features. For example, photolithographyis commonly used to pattern these features. Typically, photolithographyinvolves passing light through a reticle and focusing the light onto aphotochemically-active photoresist material. As a result, the ultimateresolution of lithography techniques is limited by factors such asoptics and light or radiation wavelength.

In conjunction with radiation of a particular wavelength,photolithography utilizes photoresist compatible with that radiation.After being developed, the photoresist acts as a mask to transfer apattern to an underlying material. The photoresist is sufficientlyrobust to withstand the development step without deforming and is alsosufficiently robust to withstand an etch for transferring the maskpattern to an underlying material. As feature sizes decrease, however,the widths of the photoresist mask features also decrease, but typicallywithout a corresponding decrease in the heights of these mask features.Due to the high aspect ratio of these mask features, it may be difficultto maintain the structural integrity of these thin mask features duringthe development and pattern transfer steps. Thus, the availability ofsufficiently robust photoresist materials can limit the ability ofphotolithography to print features, as those features continue todecrease in size.

Accordingly, there is a continuing need for high resolution methods topattern features.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the Detailed Descriptionand from the appended drawings, which are meant to illustrate and not tolimit the invention.

FIGS. 1A and 1B are schematic cross-sectional side and top plan views ofa partially formed structure, in accordance with some embodiments of theinvention.

FIGS. 2A and 2B are schematic cross-sectional side and top plan views ofthe partially formed structure of FIGS. 1A and 1B after forming anopening in a sacrificial layer, in accordance with some embodiments ofthe invention.

FIGS. 3A and 3B are schematic cross-sectional side and top plan views ofthe partially formed structure of FIGS. 2A and 2B after depositing aseed wall, in accordance with some embodiments of the invention.

FIGS. 4A and 4B are schematic cross-sectional side and top plan views ofthe partially formed structure of FIGS. 3A and 3B after definingopenings for deposition inhibiting sidewalls, in accordance with someembodiments of the invention.

FIGS. 5A, 5B and 5C are schematic cross-sectional side and top planviews of the partially formed structure of FIGS. 4A and 4B after formingdeposition inhibiting sidewalls and a deposition inhibiting cap layer,in accordance with some embodiments of the invention.

FIGS. 6A and 6B are schematic cross-sectional side and top plan views ofthe partially formed structure of FIGS. 5A and 5B after defining anopening exposing sacrificial material, in accordance with someembodiments of the invention.

FIG. 7 is a schematic, cross-sectional side view of the partially formedstructure of FIGS. 6A and 6B after removing sacrificial material to forma mold having an open volume, in accordance with some embodiments of theinvention.

FIG. 8 is a schematic perspective view of the partially formed structureof FIG. 7, in accordance with some embodiments of the invention.

FIGS. 9A and 9B are schematic cross-sectional side and top plan views ofthe partially formed structure of FIGS. 7 and 8 after selectivelydepositing alternating rows of material in the mold, in accordance withsome embodiments of the invention.

FIGS. 10A, 10B and 10C are schematic cross-sectional side and top planviews of the partially formed structure of FIGS. 9A and 9B afterselectively removing depositing inhibiting sidewalls, the depositinginhibiting cap layer and one of the alternating rows of material, inaccordance with some embodiments of the invention.

FIG. 11 is a schematic perspective view of the partially formedstructure of FIGS. 9A and 9B after forming another mold overlying theselectively deposited alternating rows and depositing a second set ofalternating rows of material in the other mold, in accordance with someembodiments of the invention.

FIG. 12 is a schematic, cross-sectional side view of the partiallyformed structure of FIG. 11 after removing the sidewalls and cap layerof the other mold, in accordance with some embodiments of the invention.

FIGS. 13A and 13B are schematic cross-sectional side and top plan viewsof the partially formed structure of FIG. 12 after selectively removingexposed parts of one of the rows in each of the sets of alternatingrows, in accordance with some embodiments of the invention.

DETAILED DESCRIPTION

Embodiments of the invention allow for the formation of exceptionallysmall features by selectively depositing material. A verticallyextending surface, e.g., a sidewall, provides a template and a seedsurface for the selective deposition of a first material. A secondmaterial is then selectively deposited on the first material. Byalternating the deposition of two or more materials, alternating rows ofthe first and second materials, and optionally more materials, can beformed. One of the deposited materials is selectively removed. Inembodiments where more than two materials are deposited, a plurality ofmaterials can be removed. Advantageously, in some embodiments, theremaining rows of materials can form structures in a final product,thereby avoiding the costs and lower throughput associated with themultiple pattern formation and pattern transfer steps common to someintegrated circuit fabrication processes. In some other embodiments, thefree-standing rows can be used as hard masks for patterning anunderlying substrate. In these applications, embodiments of theinvention can avoid expensive and complicated lithography-basedprocesses typically used to pattern small features.

It will be appreciated that deposition processes typically depositmaterial on all exposed surfaces. To selectively deposit on the seedsurface, other exposed surfaces are formed of, or coated by, depositioninhibiting material. For example, in some embodiments, the seed surfaceis formed of a conductive material that facilitates electrochemicaldeposition on that surface, while other surfaces are formed of aninsulating material that inhibits electrochemical deposition on thosesurfaces. As another example, in some other embodiments, the seedsurface is formed of a material that allows chemical vapor deposition onthat surface, while the other exposed surfaces include depositioninhibiting materials.

In some embodiments, the seed surface is provided in a mold having anopening. The ceiling, floor and sidewalls that define the interiorvolume of the mold having exposed deposition inhibiting surfaces. Theseed surface forms an interior sidewall of the mold and the openingallows deposition precursors to enter the mold and deposit on the seedsidewall. The deposited material grows laterally, so that alternatingrows of material also grow laterally within the mold. The height of themold opening determines the height of the rows and the length of therows is determined by the distance between opposing depositioninhibiting sidewalls at opposite ends of the rows. After the depositionof the rows of material, the mold can be selectively removed. Inaddition, desired rows of the deposited material can be removed to formfree-standing, laterally-spaced rows formed of the remaining depositedmaterial.

Advantageously, the deposition process controls the widths of the rows.In some embodiments, the deposition process can form rows that arethinner than rows that can be directly patterned by typical lithographicprocesses, such as 193 nm or 248 nm wavelength systems. Thus,sublithographic features can be formed. For example, features having acritical dimension in the range of about 1 nm to about 100 nm, or about2 nm to about 50 nm, or about 3 nm to about 30 can be formed

Reference will now be made to the Figures, wherein like numerals referto like parts throughout. It will be appreciated that the Figures arenot necessarily drawn to scale.

In a first phase of methods according to some embodiments, a mold havinga seed wall is formed. With reference to FIGS. 1A and 1B,cross-sectional side and top plan views of a partially formed structure100 are illustrated. It will be appreciated that the partially formedstructure 100 is a partially formed integrated circuit in someembodiments.

With continued reference to FIGS. 1A and 1B, a substrate 110 is overlaidby a bottom deposition inhibiting layer 120, which is overlaid by alayer 130 of sacrificial material. The layers 120, 130 can be depositedby various deposition processes known in the art, the processes selecteddepending on the identity of the material to be deposited. Examples ofdeposition processes include vapor deposition processes, such aschemical vapor deposition (CVD), and spin on deposition processes.

The substrate 110 can be various objects over which a pattern will beformed. The substrate 110 can include a single material, a plurality oflayers of different materials, a layer or layers having regions ofdifferent materials or different structures in them, etc. In someembodiments, these materials can include semiconductors, insulators,conductors, or combinations thereof. For example, the substrate cancomprise doped polysilicon, a single crystal electrical device activearea, a silicide, or a metal layer, such as a tungsten, aluminum orcopper layer, or combinations thereof. In some embodiments, thesubstrate 110 includes a silicon wafer.

The bottom deposition inhibiting layer 120 can be deposited over thesubstrate 110 as a separate material, or can be formed by reaction ofthe substrate 110 to form a deposition inhibiting surface. The bottomdeposition inhibiting layer 120 is chosen based upon the material to bedeposited on the seed surface, the deposition process used to depositthe material and processing compatibility with other materials utilizedwith the partially formed structure 100.

The sacrificial material forming the sacrificial layer 130 isselectively removable relative to other exposed materials in thepartially fabricated structure 100. An etch is “selective” to a materialif the etch removes that material without removing a substantial amountof other material(s) exposed to the same etch. An example of asacrificial material is, without limitation, molybdenum.

With reference to FIGS. 2A and 2B, the sacrificial layer 130 is etchedto form a seed trench 140. The seed trench 140 is sized and shaped toaccommodate a later-formed seed material, as discussed herein. It willbe appreciated that the seed trench 140 can be formed by subjecting thesacrificial layer 130 to various pattern forming processes. For example,in some embodiments, a selectively definable layer (not shown) isprovided over the layer 130. The selectively definable layer can be aphotoresist layer. The photoresist layer is exposed to radiation througha reticle and then developed to leave a pattern including openingscorresponding to the seed trench 140. The pattern in the photoresistlayer is then transferred to the sacrificial layer 130 to form the seedtrench 140.

With reference to FIGS. 3A and 3B, a seed material is formed in the seedtrench 140. The seed material can be deposited into the trench, e.g., bychemical vapor deposition, to form a seed wall 150.

With reference to FIGS. 4A and 4B, sidewall trenches 160 a, 160 b areformed by various pattern forming processes known in the art. In someembodiments, a selectively definable layer (not shown), e.g., aphotoresist layer, is provided over the layer 130. The photoresist layeris then exposed to radiation through a reticle and then developed toleave a pattern with openings corresponding to the sidewall trenches 160a, 160 b. The pattern is transferred to the sacrificial layer 130 toform the sidewall trenches 160 a, 160 b.

The sidewall trenches 160 a, 160 b are subsequently filled withdeposition inhibiting material to form deposition inhibiting sidewalls.The sidewall trenches 160 a, 160 b contact at least a portion of theseed wall 150 and partially partition off a mass or volume ofsacrificial material 132 in the layer 130.

With reference to FIGS. 5A, 5B and 5C, a deposition-inhibiting cap layer170 is formed over the sacrificial layer 130 and the seed wall 150. Inthe illustrated embodiment, the deposition inhibiting cap layer 170 isdeposited directly on the sacrificial layer 130 and the seed wall 150.With reference to FIGS. 5B and 5C, the deposited deposition inhibitingmaterial fills the trenches 160 a, 160 b (FIG. 4B) to form depositioninhibiting sidewalls 170 a, 170 b. It will be appreciated that FIG. 5Bshows, in dotted lines, the locations of the sidewalls 170 a, 170 bunderneath the layer 170 a.

With reference to FIGS. 6A and 6B, the deposition inhibiting cap layer170 is etched to define an opening 180 that exposes the sacrificialmaterial 132. The location of the opening 180 is chosen to facilitatelater removal of the sacrificial layer 130 and also to facilitate laterselective deposition of materials beneath the layer 170.

The opening 180 can be formed by various patterning forming and etchingmethods known in the art. For example, in some embodiments, aphotoresist layer (not shown) is deposited over the depositioninhibiting cap layer 170. The photoresist layer is then patterned toform openings corresponding to the sidewall openings 180. The pattern isthen transferred to the deposition inhibiting cap layer 170 to form theopenings 180. The transfer can be accomplished using an anisotropicetch.

With reference to FIGS. 7 and 8, the sacrificial layer 130 is removed,leaving a cavity 180 a. The cavity 180 a is delimited by the depositioninhibiting layers 120, 170 (forming a floor and ceiling, respectively,of the cavity 180 a) and the deposition inhibiting sidewalls 170 a, 170b, which together form a mold 172, with the cavity 180 a being aninterior volume of the mold 172. The seed sidewall 150 is disposed atone end of the cavity 180 a.

With reference to FIGS. 9A and 9B, a plurality of alternating maskmaterials are formed. In the illustrated embodiments, two materials aredeposited. A first masking material is deposited on the seed wall 150.The first masking material is chosen to preferentially deposit on theseed wall 150 relative to the deposition inhibiting layers 120, 170 andalso relative to the deposition inhibiting sidewalls 170 a, 170 b. Thedeposited first masking material forms a first row 200. The depositioncontinues until the row 200 reaches a desired width 202. The width 202is approximately equal to the desired critical dimension of a featureformed using the row 200, or to an open volume having a desired width,in embodiments where the row 200 is removed.

The first row 200 roughly tracks the contours of the seed wall 150.While the seed wall 150 is illustrated extending lengthwise in astraight line for ease of illustration and description, in otherembodiments, the seed wall 150 can curve or some portions of the wall150 can extend at an angle relative to other portions. In someembodiments, the path of the wall 150 corresponds to the shape of thedesired path of interconnects in an integrated circuit.

With continued reference to FIGS. 9A and 9B, a second material isdeposited on an exposed side of the first row 200. The second materialis chosen to preferentially deposit on the second row relative to thedeposition inhibiting layers 120, 170 and also relative to thedeposition inhibiting sidewalls 170 a, 170 b. The deposition of thesecond material continues to form a second row 210 having a desiredwidth 212. The width 212 is equal to the desired critical dimension of afeature formed using the second rows 210 or, where the second rows 210are to be removed, the width 212 is equal to a desired spacing betweenthe first rows 200.

The deposition of the first and second materials continues inalternating fashion to form a plurality of alternating first rows 200 ofthe first material and second rows 210 of the second material. Thealternating depositions are continued until a desired number of rows200, 210 are formed. The deposition can be accomplished by, e.g.,electrochemical deposition, chemical vapor deposition, or atomic layerdeposition, depending on the materials forming the seed wall 150 and thefirst and second masking materials of the rows 200, 210, respectively.Preferably, the lateral distance between the opening 180 and the seedwall 150 (FIGS. 6A and 6B) is sufficiently large to extend over alldesired rows 200, 210.

The first and second materials for the first and second rows 200, 210are chosen to be selectively removable relative to each other. Thematerials forming the deposition inhibiting cap layer 170 and thesidewalls 170 a, 170 b are also chosen to be selectively removablerelative to the row of the rows 200, 210 that is to be retained. In theillustrated embodiment, the row 200 is to be retained and other exposedmaterials are selectively removable relative to that row 200.

With reference to FIGS. 10A and 10B, the deposition inhibiting cap layer170 and the sidewalls 170 a, 170 b are selectively removed. The removalcan be accomplished using a wet or dry etch. Subsequently, the secondrows 210 are removed. Separated, free-standing layers 200 are leftremaining over the bottom deposition inhibiting layer 170.

It will be appreciated that in some embodiments, the rows 200 can beused as mask features to allow a pattern transfer to an underlyingmaterial. For example, with reference to FIG. 10C, the rows 200 can beused to define a pattern in the bottom deposition inhibiting layer 120.The pattern transfer can be accomplished using an anisotropic etchselective for the bottom deposition inhibiting layer 120. In someembodiments, the pattern can be further transferred to the substrate100. The pattern transfer can define various features in the partiallyformed structure 100, including, without limitation, interconnects forconnecting electrical devices, preferably devices arranged in an array,such as the electrical devices which form a logic array or memory cellsin the array region of a memory circuit. In some embodiments, substrate100 includes a metal and the rows 200 directly define interconnects inthe metal. In some other embodiments, the substrate 100 includes aninsulator and the rows 200 define trenches that are later filled withmetal to form interconnects.

In other embodiments, the rows 200 can be used as mandrels in a pitchmultiplication process. Pitch multiplication is disclosed in U.S. Pat.No. 5,328,810 to Lowrey et al. and U.S. Pat. No. 7,253,118 to Tran etal. For example, a blanket layer of spacer material can be deposited onthe rows 200. The blanket layer is anisotropically etched to definespacers on sidewalls of the rows 200. The rows 200 are selectivelyremoved, thereby forming free-standing spacers. The free-standingspacers are used as masking features to define patterns in underlyingmaterials. For example, the spacers can be used as mask features to etchan underlying substrate

In some other embodiments, the rows 200 can form a part of a finalstructure. For example, where the rows 200 are formed of a conductor,the rows 200 can be used as interconnects. Where the rows 200 are formedof an insulator, metal can be deposited in the spaces between the rows200 to form conductive interconnects.

With reference to FIG. 11, multiple levels of selectively deposited rowscan be formed. An underlying level of rows including the rows 200, 210is formed as discussed above with reference to FIGS. 1A-9A. Thedeposition inhibiting cap layer 170 is retained and a new mold is formedoverlying the layer 170, in a similar manner as discussed above withreference to FIGS. 1A-8.

FIG. 11 shows a cross-sectional perspective view in which one of thedepositing inhibiting sidewalls on each level is not shown, to allowillustrate of the orientation of rows on each level. As illustrated, thenew mold includes a seed sidewall 131, a deposition-inhibiting sidewall173, a depositing-inhibiting cap layer 175 and the deposition inhibitinglayer 170. In some embodiments, the materials forming the seed sidewall131, the deposition-inhibiting sidewall 173, and thedepositing-inhibiting cap layer 175 can be the same as that forming theseed sidewall 130, the deposition-inhibiting sidewall 170 a and thedeposition inhibiting layer 170, respectively. The new mold is formed ata desired orientation relative to the underlying rows 200, 210. In someembodiments, the new mold is oriented to form alternating rows ofdifferent masking materials which crisscross the rows 200, 210.

With continued reference to FIG. 11, rows 204 formed of the firstmaterial are formed alternating with rows 214 formed of the secondmaterial.

With reference to FIG. 12, the rows 204 and 214 are exposed. The rows204 and 214 are exposed by removing the sidewalls (including theillustrated sidewall 173 of FIG. 11) and the cap layer 175.

With reference to FIGS. 13A and 13B, exposed features formed of thesecond material are removed. A crisscrossing pattern of rows 200 and 204is formed. The rows 200, 204 define open columns in the spaces betweenthem. As noted herein, the crisscrossing pattern can be utilized as partof a final structure (e.g., crossing interconnects), or as a mask toform a pattern in underlying materials. The openings in thecrisscrossing pattern can be filled to form isolated pillar shapes,including pillars having rectangular or cubic horizontal cross-sectionalareas. Such an arrangement can be useful for forming, e.g., contactplugs. In addition, the pillars can advantageously be applied in somearrangements for patterning arrays of features, particularly densearrays of features, such as capacitors for memory applications,including DRAM, or as memory elements for MRAM or STTRAM.

It will be appreciated that the various materials for the depositioninhibiting layers 120, 170, the deposition inhibiting sidewalls 170 a,170 b, and the seed sidewall 150 are chosen based upon the materialsthat will be deposited in the cavity 180 a (FIG. 7), and based upon,e.g., etch and deposition compatibility with the other materials formingthe partially formed structure 100. For example, in some embodiments,the bottom deposition inhibiting layer 120 is formed of an insulator andthe seed wall 150 is formed of a conductor. The first and secondmaterials are deposited by electrochemical deposition. In someembodiments, gold and silver are used as the first and second materials.In another example, gold and nickel are used. Plating solutionsincluding the desired metal species can be introduced into the opening180. In some embodiments, the plating solution contains both materials.The seed wall 150 can be connected to a power source and depositionoccurs when current is flowed through the solution. In some embodiments,the seed wall 150 can be connected to a power source through thesubstrate 110. For example, the seed wall 150 can be made to extendthrough the deposition inhibiting layer 120 to contact the substrate110, which may be formed of conductive or semiconductive material andwhich is connected to one of the electrodes of the power source. Thewidth of each row can be controlled by selection of the charge passedduring the deposition and by selection of the concentrations of themetal species. For example, to increase the width of a row formed by oneof the metals, the concentration of that metal can be increased.Suitable selective deposition methods are discussed in Qin et al.,Science, Vol. 309, Jul. 1, 2005, pp. 113-115.

Once deposited and after the rows 200, 210 are exposed, one of themetals can be removed by an appropriate etch. For example, Ni can beselectively removed relative to gold using a wet etch, such as a wetetch including concentrated HNO₃. In another example, where gold andsilver are used the first and second materials, silver rows can beselectively removed using a wet etch formed of methanol, 30% ammoniumhydroxide and 30% hydrogen peroxide (4:1:1 v/v/v). Suitable etch methodsare discussed in Qin et al., Science, Vol. 309, Jul. 1, 2005, pp.113-115.

In another example, materials are selectively deposited in the cavity180 a by atomic layer deposition (ALD). In some embodiments, the seedsidewall 150 is formed of silicon, and the deposition inhibiting layers120, 170, and the deposition inhibiting sidewalls 170 a, 170 b areformed of silicon oxide having a chemically modified surface. Thedeposition inhibiting layers 120, 170, and the deposition inhibitingsidewalls 170 a, 170 b are formed as described above, and then exposedto another chemical species to form a deposition inhibiting layer onexposed silicon oxide surfaces. For example, octadecyltrichlorosilane(ODTS) can be provided to the cavity 180 a, where it is selectivelyadsorbed on silicon oxide surfaces relative to the silicon seed sidewall150. The ODTS forms a self-assembled monolayer (SAM) on the surfaces ofthe deposition inhibiting layers 120, 170, and the deposition inhibitingsidewalls 170 a, 170 b.

Next, the row 200 is formed by selective atomic layer deposition on theseed sidewall 150. For example, the row 200 can be formed of HfO₂deposited using tetrakis(dimethylamido)hafnium(IV) (Hf[N(CH₃)₂]₄ andwater. Suitable methods for forming deposition inhibiting surfaces anddepositing HfO₂ are discussed in Chen, Applied Physics Letters 86,191910 (2005).

The row 210 is subsequently selectively deposited by atomic layerdeposition on the deposited row 200. For example, ruthenium (Ru) isdeposited on the sidewall of the HfO₂ row 200 to form the row 210.Suitable methods for selectively depositing Ru are discussed in Park,Applied Physics Letters 86, 051903 (2005).

The deposition of the HfO₂ and the Ru are alternately repeated to form adesired number of rows 200, 210. Subsequently, the rows 200, 210 areexposed, as discussed herein, and one of the rows is removed by exposureto etchant, e.g., in a wet etch selective for the material of one of therows 200, 210 relative to other exposed materials.

In some embodiments, the inside surfaces of the cavity 180 a are exposedto ODTS one or more times during the deposition of the rows 200, 210 tobuild up the ODTS layer on those inside surfaces.

Advantageously, atomic layer deposition allows the rows 200, 210 to beformed with high precision regarding the widths 202, 212, since thewidths can be controlled by the number of deposition cycles performed,as known in the art. As a result, exceptionally uniform rows 200, 210can be formed. In some other applications, the layer by layer depositionmechanism of ALD allows the formation, as desired, of rows 200, 210having different widths.

In addition to forming integrated circuits, it will be appreciated thatthe selectively deposited rows disclosed herein can be used in variousother applications where the formation of patterns with very smallfeatures is desired. For example, the preferred embodiments can beapplied to form gratings, disk drives, storage media or templates ormasks for other lithography techniques, including X-ray or imprintlithography. In other applications, multiple levels of the rows can beutilized in various light bending applications, in which spatiallyisolated blocks of material are formed “floating” and separated fromother blocks of materials.

Floating blocks of material can be formed by depositing material intovias formed by crisscrossing rows of masking material (FIG. 13B) and thevias can be overlaid with material and additional vias can be formed andfilled at a higher level. In other cases, the blocks of material can bethe first or second masking materials themselves, with the moldsdimensioned to form short blocks, rather than long rows of maskingmaterial. The deposition inhibiting material can be used to separateneighboring pluralities of the blocks.

It will be appreciated that only a section of the partially-formedstructure 100 is shown. In some embodiments, a plurality of the molds172 can be formed across the surface of the substrate 110 in a desiredpattern. For example, the molds 172 can be formed in a regular arrayover the substrate 110 to pattern a regular array of features. Forexample, these features can be advantageously applied to form featuresin integrated circuit utilizing arrays of features, e.g., to form logiccircuitry or memory devices, including flash memory or DRAM.

Also, while “processing” through a mask preferably involves etchingunderlying material(s), processing through the mask can involvesubjecting material(s) underlying the mask materials to anysemiconductor fabrication process. For example, processing can involveion implantation, diffusion doping, depositing, oxidizing (particularlywith use of a hard mask under the polymer mask), nitridizing, etc.through the mask layers and onto underlying layers. In addition, themask can be used as a stop or barrier for chemical mechanical polishing(CMP) or CMP can be performed on various material(s) to allow for bothplanarization and etching.

It will be appreciated from the description herein that the inventionincludes various aspects. For example, according to one aspect of theinvention, a patterning method is provided. The method comprisesproviding a substrate having a top surface that comprises a depositioninhibiting material. A mass of a sacrificial material is provided overthe deposition inhibiting material. A seed wall is formed on one side ofthe mass of the sacrificial material. First and second depositioninhibiting walls are formed on opposite sides of the mass of thesacrificial material. The seed wall is disposed between and contactingthe first and second deposition inhibiting walls. A depositioninhibiting cap layer is formed over the mass of the sacrificialmaterial. The mass of the sacrificial material is selectively removed toform an open volume at least partially bounded by the seed wall, thefirst and second deposition inhibiting walls, the deposition inhibitingmaterial and the cap layer. First and second materials are alternatinglydeposited in the open volume.

According to another aspect of the invention, a method for forming apattern is provided. The method comprises providing a substrate. Ahollow mold is provided overlying the substrate. The mold has an openinginto an open internal volume and a seed sidewall partially delimitingthe open volume. A first material is selectively deposited on the seedsidewall in the open volume. A second material is selectively depositedon a side of the first material in the open volume.

According to yet another aspect of the invention, a method fordepositing materials in a desired pattern is provided. The methodcomprises providing a substrate. The substrate is alternatingly exposedto first and second material precursors to deposit first and secondmaterials on a first level. Depositing the first and second materialssequentially laterally grows a first plurality of alternating rows ofthe first and the second materials. One of the first and secondmaterials is selectively removed relative to the other of the first andsecond materials.

In addition to the above disclosure, it will also be appreciated bythose skilled in the art that various omissions, additions andmodifications may be made to the methods and structures described abovewithout departing from the scope of the invention. All suchmodifications and changes are intended to fall within the scope of theinvention, as defined by the appended claims.

I claim:
 1. A method for semiconductor processing, comprising:alternatingly exposing a substrate to first and second materialprecursors to deposit first and second materials on a first level,wherein alternatingly exposing the substrate to first and secondmaterial precursors sequentially laterally grows a first plurality ofalternating rows of the first and the second materials on the firstlevel, wherein the rows alternate as seen from in top-down view; andselectively removing one of the first and second materials relative tothe other of the first and second materials.
 2. The method of claim 1,wherein the other of the first and second materials defines a maskpattern, and further comprising transferring the pattern to thesubstrate.
 3. The method of claim 1, further comprising sequentiallylaterally growing a second plurality of alternating rows of the firstand second materials on a second level, the second plurality ofalternating rows crossing the first plurality of alternating rows. 4.The method of claim 3, wherein growing the second plurality ofalternating rows is performed before selectively removing the one of thefirst and second materials.
 5. The method of claim 4, wherein the secondplurality of alternating rows is vertically separated from the firstplurality of alternating rows by a deposition inhibiting layer.
 6. Themethod of claim 5, further comprising forming a plurality of laterallyseparated open columns by a process comprising: selectively removing theone of the first and second materials on the second level, therebyexposing portions of the deposition inhibiting layer; subsequentlyselectively removing the exposed portions of the deposition inhibitinglayer, thereby exposing portions of the one of the first and secondmaterials on the first level; and selectively removing the exposedportions of the one of the first and second materials on the first levelto define the open columns.
 7. The method of claim 6, wherein furthercomprising depositing a fill material into the open columns.
 8. Themethod of claim 7, further comprising forming a plurality of verticallyand laterally separated blocks of the fill material by a processcomprising: removing material on the second level; forming an otherdeposition inhibiting material over the second level; sequentiallylaterally growing a third plurality of alternating rows of the first andsecond materials on a third level; forming a second other depositioninhibiting material over the third plurality of alternating rows;sequentially laterally growing a fourth plurality of alternating rows ofthe first and second materials on a fourth level, the fourth pluralityof alternating rows crossing the third plurality of alternating rows;removing the one of the first and second materials on the fourth level,thereby exposing portions of the other deposition inhibiting material;removing the exposed portions of the other deposition inhibitingmaterial, thereby exposing portions of the one of the first and secondmaterials on the third level; removing the exposed portions of the oneof the first and second materials on the third level to form laterallyseparated openings; and filling the openings with the a material.
 9. Themethod of claim 1, wherein sequentially laterally growing the pluralityof materials comprises growing rows of one or more additional materialsin sequence with the first and second materials.
 10. The method of claim1, wherein sequentially laterally growing the plurality of materialscomprises electroplating the materials.
 11. The method of claim 10,wherein electroplating the materials comprises electroplating gold andnickel.
 12. The method of claim 10, wherein selectively removing thefirst material comprises etching the nickel with HNO₃.
 13. The method ofclaim 1, wherein sequentially laterally growing the plurality ofmaterials comprises atomic layer depositing the materials.
 14. A methodfor semiconductor processing, comprising: a seed wall extendingvertically from a substrate; alternatingly depositing rows of a firstmaterial and rows of a second material along a side of the seed wall,each of the rows extending vertically from the substrate; andselectively removing one of rows of the first or second materialsrelative to the other of the rows of the first and second materials. 15.The method of claim 14, further comprising depositing a depositioninhibiting material over the substrate before depositing alternatingrows of the first and second materials, wherein the depositioninhibiting material limits deposition of the first and second materialson the substrate.
 16. The method of claim 14, wherein the rows extendsubstantially parallel to the seed wall.
 17. The method of claim 14,wherein providing the seed wall comprises: depositing a sacrificialmaterial over the substrate; forming a trench in the sacrificialmaterial; depositing material forming the seed wall into the trench; andselectively removing the sacrificial material.
 18. The method of claim14, wherein the other of the rows of the first and second materialsdefines a mask having a pattern, and further comprising etching thesubstrate through the mask to transfer the mask pattern to thesubstrate.
 19. The method of claim 18, wherein etching the substratethrough the mask defines interconnects in the substrate.
 20. The methodof claim 14, wherein depositing rows of a first material comprisesperforming a vapor deposition process.
 21. The method of claim 20,wherein depositing rows of a second material comprises performing avapor deposition process.